1. Field of the Invention
The present invention relates to a light emitting element for use in a laser apparatus.
2. Description of the Prior Art
A conventional light emitting element employing an epitaxial layer of III-V nitride-based mixed crystal, such as GaN, uses sapphire (.alpha.-Al.sub.2 O.sub.3) as its substrate crystal.
GaN has a wurtzite type crystal structure, while sapphire serving as the substrate crystal has a corundum type crystal structure. Although both are of a hexagonal system, they are not equivalent; the atomic surface of sapphire has a thirteen repetition periods. Further, GaN and sapphire have significantly different lattice constants and their mutual lattice unmatching goes up to 14%. It is difficult to form a good epitaxial layer because of such lattice unmatching, thus preventing the light emitting elements using these materials from providing light emission with high efficiency.